Morel Mushroom Forecast: Soil Degree Days by State
Morels come up on the soil, not the calendar. This reads the soil temperature where you walk, adds it up the way the published predictor does, and shows it against the 410 degree day threshold, day by day for a week.
Read the soil where you hunt
Enter a ZIP code. The forecast reads hourly soil temperature at 6 cm for that spot, which is 2.4 inches and the depth the published threshold is measured at, sums every degree above freezing over the last 20 days, counts the rain events behind it, and rates each of the next seven days Dormant, Waking, Close, Good, Prime.
The soil tells you, and it has a number
Jeanne Mihail put soil and air temperature loggers in Missouri morel ground and worked out what the fruiting followed. The answer was accumulated temperature rather than any single warm afternoon: add up every degree above 32 F that the soil holds over a stretch of days and the fruiting arrives at a repeatable total. For a 20 day window at two inches that total is 410. Air temperature accumulates faster and has its own figure for the same window, which the forecast keeps as its second reading.
That is the whole base of the score. Everything below either confirms it or caps it. The floor comes from the Puget Sound Mycological Society, which puts a soil temperature under which nothing happens at 40 F, and the decay at the top end comes from the same work that set the threshold: the optimum is narrow, and well past it the fruiting is behind you rather than ahead.
Soil degree days
sets the base, 8 to 80
Daily mean soil temperature above 32 F summed over the trailing 20 days, read at 6 cm, against the published threshold of 410.
The sources behind it
“The best predictor of first yellow morel appearance was the accumulated average soil temperature above freezing (32 °F) over the preceding twenty days. However, first yellow morel appearance seems to be delayed beyond the prediction when winters have been especially warm.”
Predicting the Spring Morel Season The whole model rests here. Not a single soil reading on one afternoon: the sum of daily mean soil temperature above freezing over the preceding twenty days, measured at two inches. The published threshold for that sum is 410 degree days Fahrenheit.
“Winter chilling, as well as spring soil warming, are both important in determining the when we will first see early spring morels.”
Predicting the Spring Morel Season Soil warming is necessary and not sufficient. The same paper publishes four thresholds, 510 and 660 degree days for air over twenty and thirty days and 410 and 520 for soil, which is why a soil reading is preferred here and an air reading is the fallback.
Past the optimum
the base falls away above 1.6 times the threshold
The response is a band. Well past the optimum the flush is over, so the base decays instead of climbing.
The sources behind it
“Fruiting season length was positively correlated with soil warming, suggesting that a narrow range of optimum soil temperatures favour the explosive production of fruit bodies.”
Spatial and temporal patterns of morel fruiting The response is a band, not a staircase. Past the optimum the flush ends, which is why the score here peaks and then falls instead of climbing with every warm day.
The 40 degree floor
caps the day at 14
A seven day mean soil temperature under 40 F holds the day at Dormant however the degree days read.
The sources behind it
“Eastern Washington morels, the subject of this article, need at least a consistent ground and air temperature of +40ºF to start fruiting. The timing of the fruiting varies from year to year, sometimes starting as early as March and in other years as late as mid May.”
Spore Prints 501: morels of eastern Washington A floor, in a mycological society bulletin, and the spread of start dates around it. Below a consistent 40 degrees the forecast does not rate a day above Dormant however the degree days read.
Snow still on it
caps the day at 18
Measurable snow depth holds the day down. Snowmelt comes first in the sequence.
The sources behind it
“The bottom line is that morels fruit when winter snow has melted, the soil is beginning to warm, and the air is still humid.”
Ecology and Management of Morels Harvested From the Forests of Western North America Three conditions in one federal sentence, and the order they come in. Snow on the ground holds the day down no matter what the degree days say.
Air degree days
the base when no soil reading comes back
The same trailing 20 day sum on air temperature, against the published air threshold of 510 rather than 410.
The sources behind it
“Winter chilling, as well as spring soil warming, are both important in determining the when we will first see early spring morels.”
Predicting the Spring Morel Season Soil warming is necessary and not sufficient. The same paper publishes four thresholds, 510 and 660 degree days for air over twenty and thirty days and 410 and 520 for soil, which is why a soil reading is preferred here and an air reading is the fallback.
The sources
- Yellow Morel (Common Morel), Morchella esculentoides Missouri Department of Conservation. MDC Field Guide, 2026. A state wildlife agency on what a true morel looks like, what it grows under, and what the dangerous lookalikes look like instead.
- Big Red False Morel, Gyromitra caroliniana Missouri Department of Conservation. MDC Field Guide, 2026. The false morel in the agency’s own words, including the two sentences that settle the "but I know someone who eats them" argument.
- Accumulated Growing Degree Day maps USA National Phenology Network. USA-NPN, 2026. The national phenology maps, and the definition that keeps their accumulation from being confused with the trailing twenty day sum this forecast uses.
- Status of Spring: the First Leaf and First Bloom Indices USA National Phenology Network. USA-NPN, 2026. The national index of when spring arrives, built on the leaf out of lilacs and honeysuckles and checked against volunteer observations.
- Special Forest Products USDA Forest Service. USDA Forest Service, national programme page, 2026. The federal definition that puts mushrooms inside the special forest products programme, which is the reason a national forest district office is the office to ring.
- 36 CFR 261.6, Timber and other forest products Code of Federal Regulations. Electronic Code of Federal Regulations, title 36, chapter II, part 261, 2026. The prohibition every national forest permit is written against. It is the governing section, not the timber sale subparts the blogs cite.
- A 19-year longitudinal assessment of gyromitrin-containing (Gyromitra spp.) mushroom poisonings in Michigan Vohra, V.; Dirks, M.; Bonito, G.; James, T.; Carroll, A.. Toxicon 247: 107825, 2024. Nineteen years of poison centre calls from one state, which is the closest thing to a real denominator on how false morel poisoning actually goes.
- Morel Mushrooms (FNH-00020) University of Alaska Fairbanks Cooperative Extension Service. UAF Cooperative Extension Service, 2021. The only extension publication written for a state whose morel season is in high summer and runs on last year burns.
- Common Wild Edible Fungi in Illinois University of Illinois Extension. University of Illinois Extension handout, 2019. Species, month and habitat on one line each, which is what separates the black morel calendar from the yellow morel calendar inside a single state.
- Predicting the Spring Morel Season Mihail, J.D.. McIlvainea 23: 53 to 60, 2014. Five springs of dated first-appearance records for yellow morels in north-central Missouri, tested against accumulated air and soil temperature over trailing windows. The paper publishes the thresholds this forecast uses.
- Spore Prints 501: morels of eastern Washington Puget Sound Mycological Society. Spore Prints, bulletin of the Puget Sound Mycological Society, no. 501, 2014. A mycological society bulletin that names a consistent ground and air temperature morels need before they fruit, and the elevation march that follows.
- 2011 NAMA Toxicology Committee Report: North American Mushroom Poisonings Beug, M.W.. North American Mycological Association, 2011. The national case report series, which is also the source for the one thing that goes wrong with true morels.
- Spatial and temporal patterns of morel fruiting Mihail, J.D.; Bruhn, J.N.; Bonello, P.. Mycological Research 111(3): 339 to 346, 2007. Fruiting onset, season length and abundance across years and plots, which separates what sets the timing from what sets the yield.
- Ecology and Management of Morels Harvested From the Forests of Western North America Pilz, D.; McLain, R.; Alexander, S.; Villarreal-Ruiz, L.; Berch, S.; Wurtz, T.L.; Parks, C.G.; McFarlane, E.; Baker, B.; Molina, R.; Smith, J.E.. USDA Forest Service General Technical Report PNW-GTR-710, 161 p., 2007. The federal synthesis on morels: moisture, snowmelt, elevation, aspect, latitude, fire severity, host trees and the toxicology of the lookalikes. Most statements name the prior author they rest on, and those attributions are kept inside the quotes.
- Harvesting Morels After Wildfire in Alaska Wurtz, T.L.; Wiita, A.L.; Weber, N.S.; Pilz, D.. USDA Forest Service Research Note PNW-RN-546, 2005. Three seasons of fieldwork in burned interior Alaska, with dated start, peak and end for the fruiting they measured.
- May is Morel Month in Michigan (Extension Bulletin E-2755) Hallen, H.; Volk, T.; Adams, G.. Michigan State University Extension, 2001. The land-grant bulletin that gives the rate at which the season moves north, and treats the indicator plants as what veteran hunters watch rather than as a measurement.
Rain changes how many, not when
The folklore has a warm rain pulling morels out of the ground three days later. What the literature supports is steadier and less dramatic: the temperature sets the timing, and the water that fell over the previous month sets the yield. So this forecast counts rain events over 10 mm in the trailing 30 days and moves the score by a few points either way, rather than putting a date three days after a shower.
Soil moisture is weighted in one direction only. Dry ground holds the fruiting back, and the published work on wetter ground does not agree with itself about the direction, so a wet reading is never allowed to add points here.
Rain events over 10 mm
minus 9 to plus 8
Counted over the trailing 30 days. It moves how many, never when: the timing is the temperature.
The sources behind it
“Fruiting onset was inversely correlated with spring air and soil temperatures, whereas abundance was positively correlated with rain events (>10mm) during the 30 d preceding fruiting.”
Spatial and temporal patterns of morel fruiting This is the sentence that splits the model in two. Temperature sets the date. Rain sets how many. So rain counts here as events over 10 mm in the trailing thirty days, and it moves the yield, never the timing.
“For instance, during the years 2001 to 2005 in north-central Missouri, the first day of morel fruiting reliably fell between the 104th and 110th days of the calendar year (mid-April) and total seasonal production was closely correlated with the number of rainfall events of greater than 10 mm during the next 2 weeks”
Ecology and Management of Morels Harvested From the Forests of Western North America The same 10 mm event threshold from the other direction, and a striking stability in the start date: five straight years inside a six day window in one place. The Forest Service carries this as a personal communication from a five year single location record, which is where its weight stops.
Soil moisture
minus 11 to 0
Volumetric water at 3 to 9 cm. The direction of the effect is contested in the literature, so it only ever takes points away at the dry and the saturated ends.
The sources behind it
“Such rainfall not only hydrates the morel mycelium that is nourishing the growing fruiting body, but likely also maintains high humidity levels near the soil surface so the growing morel does not dry out and shrivel.”
Ecology and Management of Morels Harvested From the Forests of Western North America Why moisture matters twice: in the ground for the mycelium, and in the air at ankle height for the fruiting body that is already up.
“Thompson (1994) claimed that soil moisture is only important for morel fruiting after the soil has warmed, whereas Goldway and others (2000) suggested that slowly drying soil stimulates morel fruiting.”
Ecology and Management of Morels Harvested From the Forests of Western North America The direction of the soil moisture effect is contested in the literature, which is the reason moisture here only ever takes points away at the dry and the saturated ends and never adds any.
“Morel spores germinate readily without any special requirements other than moisture (Hervey and others 1978, Schmidt 1983, Volk and others 1997, Weber 1988).”
Ecology and Management of Morels Harvested From the Forests of Western North America Four independent citations behind one claim, which is as settled as this literature gets.
Where to put your feet once the soil is ready
The soil reading tells you which weekend. The hillside is the other half of the hunt, and these four are how to pick it: the host trees, the high ground and the low, last year’s burns, and the plants that leaf out alongside the morels, each with the sentences behind it.
Lilac, mayapple, apple bloom
Shown, not scored
Lilac leaf out is a measured national index, and the early shrubs leafing out around you are a sign the spring morels follow is under way.
The sources behind it
“The First Leaf Index is based on the leaf out of lilacs and honeysuckles, which are among the first plants to show their leaves in the spring. This Index is associated with the first leafing of early-spring shrubs and other plants.”
Status of Spring: the First Leaf and First Bloom Indices Lilac leaf out is a measured national index, so the lilac is worth watching. When the early shrubs leaf out around you, the spring that morels follow is under way, and the soil reading says how far along it is.
“The USA-NPN generates daily Accumulated Growing Degree Day (AGDD) maps using a January 1 start date and two base temperatures, 32°F and 50°F.”
Accumulated Growing Degree Day maps Read this before comparing anything. The national maps accumulate from January 1. Mihail’s threshold is a rolling twenty day sum. Same base temperature, completely different magnitudes, so the 410 here is never checked against a published AGDD map.
“Growing degrees days are defined as the number of degrees the average daily temperature exceeds a base temperature, or the temperature below which the organism will remain in dormancy.”
Accumulated Growing Degree Day maps The definition the forecast computes, word for word as the page prints it.
Host trees
Shown, not scored
Dying elm, living white ash, just dead cottonwood, sycamore, tulip poplar, old apple. Where to walk, which is a different question from when.
The sources behind it
“Found especially under dying elms and living white ashes and cottonwoods; also under tulip poplars, oaks, and hickories.”
Yellow Morel (Common Morel), Morchella esculentoides A state agency on the hosts, and note the asymmetry it asserts: elms dying, ashes and cottonwoods living. That distinction is worth more than the species list.
“Weber (1988) reported morels in Michigan as associated with oak-hickory or beech-maple forests, or under sycamore, elm, ash, cottonwood, and apple trees.”
Ecology and Management of Morels Harvested From the Forests of Western North America Forest types as well as single trees, which is the scale a reader can actually see from the road.
“Kuo (2005) listed morels in the Eastern United States as associated with ash, elm, and tulip trees, and often found in old apple orchards.”
Ecology and Management of Morels Harvested From the Forests of Western North America The old apple orchard, with a citation behind it instead of folklore.
“Thompson (1994) found morels with senescent or dying apple trees, just-dead cottonwoods, and especially elms.”
Ecology and Management of Morels Harvested From the Forests of Western North America Tree health, and how narrow the window is: just dead, not long dead. Which is exactly why this is a timing product.
“Massive crops of yellow morels at the bases of dying elms (Thompson 1994, Weber 1988) and extensive fruiting of natural black morels in insect-killed forest (Pilz and others 2004) are two examples.”
Ecology and Management of Morels Harvested From the Forests of Western North America Two different disturbances feeding two different species. A dying elm for yellow morels, an insect-killed stand for black ones.
“Volk and others (1997) theorized that such mass fruiting represents a last-ditch effort to reproduce when the morel’s food source disappears.”
Ecology and Management of Morels Harvested From the Forests of Western North America Why a dead or dying host matters at all, in one sentence: the fungus is leaving, and it fruits on the way out.
“Morchella esculenta – common morel, yellow morel. May. Various habitats including under dead elms and in old apple orchards.”
Common Wild Edible Fungi in Illinois A species, a month and two habitats on one extension line. The same handout gives the black morel as April to May under dead elms and living ash, so inside one state the black morel runs a few weeks ahead of the yellow.
“it fruits in spring, likes recent burn sites, likes a mixed conifer forest as well as cottonwoods, fruits mostly on the east side of the Cascade Crest, and starts low and moves higher in elevation as the season progresses.”
Spore Prints 501: morels of eastern Washington The whole eastern Washington pattern in one clause: spring, burns, mixed conifer and cottonwood, east side, low to high.
Last year burns
Shown, not scored
Year one after a fire is the year, the red needle zone is the band, and 60 to 80 percent duff consumption is the optimum. The fire maps from last summer are the place to start looking.
The sources behind it
“The gray morel fruits in conifer forests and is found abundantly the first spring or summer after a wildfire and in reduced numbers the second postfire year. It is found in greatest abundance at high elevations and northern latitudes.”
Ecology and Management of Morels Harvested From the Forests of Western North America Year one is the year. Year two is less. And the effect is strongest high up and far north, which is why the western pages lead with last summer fire perimeters.
“Although values differ by several orders of magnitude depending on the habitat, it appears common to find 1,000 or more morels per acre the first year after a forest fire.”
Ecology and Management of Morels Harvested From the Forests of Western North America The magnitude of a first year burn, with the orders of magnitude hedge the Forest Service wrote into the same sentence.
“Commercial harvesters report fire morels fruiting in the “red needle zone,” that is, areas where the fire was hot enough to kill the trees, but not so hot that the canopy was consumed.”
Ecology and Management of Morels Harvested From the Forests of Western North America Burn severity, not burn presence. The band to walk is where the needles went red and stayed on the tree.
“Keefer (2005) likewise reported that fire morels fruited in areas where 20 to 100 percent of the duff layer was consumed by a fire, but occurred most abundantly in areas where a moderate 60 to 80 percent of the duff layer was consumed.”
Ecology and Management of Morels Harvested From the Forests of Western North America A real dose response: a wide tolerance and a clear optimum, in percent of duff consumed. It is the quantitative version of the red needle zone.
“Just after snowmelt in the spring, areas burned by fires during the previous 2 years provide the most reliable source of morels in the Sierras.”
Ecology and Management of Morels Harvested From the Forests of Western North America A two year lookback, not a ten year one, and the timing cue to go with it: just after snowmelt.
“Pilz and others (2004) reported this morel as the most abundant on their nonburned plots (both healthy and insect-killed forests) and it also fruited the second year (but not the first) following a fire on burned plots.”
Ecology and Management of Morels Harvested From the Forests of Western North America The subtlety the one line rules miss: the year one flush and the year two flush on the same burn are different species with different habits.
“Burned soils also warm more quickly than nonburned soils because the black surface absorbs infrared radiation better.”
Ecology and Management of Morels Harvested From the Forests of Western North America A burn runs ahead of unburned ground at the same elevation, because black absorbs. The soil reading is for open ground, so a burn runs early against it.
“The two major types of commercially harvested morels in western Montana are the burn morels and gray morels.”
Ecology and Management of Morels Harvested From the Forests of Western North America What the commercial pickers in western Montana are actually sorting into buckets.
Elevation and aspect
Shown, not scored
Low ground and south faces first, then higher and north-facing. Follow the season uphill and around to the north faces as the weeks go on.
The sources behind it
“In areas that have hilly or mountainous topography, morels will fruit first at low elevation or on south-facing slopes that warm up early, then at higher elevations and on north-facing slopes that warm up later (Low 1995).”
Ecology and Management of Morels Harvested From the Forests of Western North America Elevation and aspect in one federal sentence. Low ground and south faces first, then the high ground and the north faces, which is the order to walk a hillside in as the season climbs it.
“Morels frequently occur in moist microhabitats and the morel season progresses upwards in elevation as summer weather warms (Miller 2003).”
Ecology and Management of Morels Harvested From the Forests of Western North America The interior West pattern, independent of the Sierra statement, and it pairs the climb with the moist pockets that hold on after the open ground quits.
“Fruiting generally starts in early March at about 4,000 feet in the northern Sierras and about 5,000 feet in the southern Sierras, and increases in elevation as spring progresses.”
Ecology and Management of Morels Harvested From the Forests of Western North America The one quantified elevation band in the government literature: a start month, a start elevation, and a thousand feet of latitude adjustment inside one state.
“Because this region lies in the rain shadow of the Cascade Range to the west, the mesic coniferous forest habitat that morels inhabit is found at fairly high elevations ranging from 2,500 to 7,000 feet.”
Ecology and Management of Morels Harvested From the Forests of Western North America Why the northern Rockies pages point high rather than low: in the rain shadow the habitat itself sits at 2,500 to 7,000 feet.
“In some cases, such as in Nevada and Utah, morel habitat occurs as isolated islands near or on mountain peaks.”
Ecology and Management of Morels Harvested From the Forests of Western North America In the Great Basin the habitat is an archipelago, so the state reading means less than the range reading and the pages say which ranges.
The season also moves, and at a rate an extension bulletin publishes: the front begins in the south and travels north about a hundred miles a week. That rate is what draws the window on each of the 50 state pages, and the Forest Service synthesis gives the same figure independently.
The state window
minus 55 well outside it, plus 3 in the opening fortnight
Each state window steps north at the published rate of about 100 miles a week. The live soil reading outranks it inside the window.
The sources behind it
“The morel season generally begins in the south and progresses 100 miles or more north per week.”
May is Morel Month in Michigan (Extension Bulletin E-2755) The rate the national map is drawn at. A land-grant extension bulletin, and it matches the Forest Service synthesis independently.
“Lonik (2002) reported that in the Eastern United States, the morel season moves south to north at about 100 miles per week.”
Ecology and Management of Morels Harvested From the Forests of Western North America The same rate in a federal report, attributed to a popular book. Two sources agreeing on 100 miles a week is why the state windows step the way they do. It is a latitude rate, from the Gulf to the northern tier.
“In any one location, the season can last from several weeks to several months depending on rainfall, humidity, topography, and the morel species.”
Ecology and Management of Morels Harvested From the Forests of Western North America Why each state window here is a band with a middle rather than a date, and why the live reading outranks the band on any given weekend.
The usual window, state by state
These bands are drawn from the published rate the season travels north at, anchored on the reference point in each state. They are the starting guess a page makes before it has read anything. Inside those dates the live soil reading outranks them, which is the point of the tool above.
| State | Usual window | Middle of it | Host trees to walk |
|---|---|---|---|
| Alabama | March 1 to April 10 | March | dying elm, living white ash, tulip poplar |
| Alaska | June 5 to July 25 | June | burned black spruce, birch, aspen |
| Arizona | March 25 to June 15 | May | ponderosa pine duff, burned conifer, cottonwood along water |
| Arkansas | March 10 to April 22 | March | dying elm, living white ash, just dead cottonwood |
| California | March 1 to July 1 | April | burned conifer, cottonwood, oak woodland |
| Colorado | April 20 to July 1 | May | burned conifer, aspen, cottonwood along water |
| Connecticut | April 15 to May 22 | May | dying elm, living white ash, old apple |
| Delaware | April 2 to May 6 | April | just dead cottonwood, sycamore, tulip poplar |
| Florida | February 20 to March 31 | March | dying elm, sycamore, river bottom hardwood |
| Georgia | March 5 to April 15 | March | tulip poplar, dying elm, living white ash |
| Hawaii | Rated on the soil reading | Year round forest | koa and ohia forest, introduced hardwood |
| Idaho | April 10 to July 5 | May | burned conifer, cottonwood, grand fir duff |
| Illinois | April 1 to May 10 | April | dead elm, living ash, old apple orchard |
| Indiana | April 2 to May 12 | April | dying elm, living white ash, just dead cottonwood |
| Iowa | April 8 to May 15 | April | dying elm, just dead cottonwood, living white ash |
| Kansas | March 28 to May 5 | April | dying elm, just dead cottonwood, sycamore |
| Kentucky | March 25 to May 5 | April | dying elm, living white ash, tulip poplar |
| Louisiana | February 25 to April 5 | March | sycamore, dying elm, river bottom hardwood |
| Maine | April 28 to June 5 | May | old apple, dying elm, living white ash |
| Maryland | April 1 to May 8 | April | tulip poplar, dying elm, living white ash |
| Massachusetts | April 18 to May 26 | May | old apple, dying elm, living white ash |
| Michigan | April 20 to June 2 | May | sycamore, dying elm, living ash |
| Minnesota | April 25 to June 5 | May | dying elm, just dead cottonwood, living white ash |
| Mississippi | March 1 to April 8 | March | dying elm, sycamore, living white ash |
| Missouri | March 28 to May 6 | April | dying elm, living white ash, living cottonwood |
| Montana | April 20 to July 8 | May | burned conifer, cottonwood, aspen |
| Nebraska | April 5 to May 12 | April | just dead cottonwood, dying elm, sycamore |
| Nevada | April 15 to June 30 | May | burned conifer, aspen, cottonwood along water |
| New Hampshire | April 22 to May 30 | May | old apple, dying elm, living white ash |
| New Jersey | April 5 to May 10 | April | tulip poplar, dying elm, sycamore |
| New Mexico | April 1 to June 20 | May | burned conifer, ponderosa duff, aspen |
| New York | April 15 to May 25 | May | dying elm, living white ash, old apple |
| North Carolina | March 18 to May 2 | April | tulip poplar, dying elm, living white ash |
| North Dakota | April 25 to June 4 | May | just dead cottonwood, dying elm, green ash |
| Ohio | April 5 to May 14 | April | dying elm, living white ash, tulip poplar |
| Oklahoma | March 12 to April 22 | March | dying elm, just dead cottonwood, sycamore |
| Oregon | April 1 to July 5 | May | burned conifer, cottonwood, mixed conifer duff |
| Pennsylvania | April 8 to May 18 | April | dying elm, living white ash, tulip poplar |
| Rhode Island | April 16 to May 22 | May | old apple, dying elm, living white ash |
| South Carolina | March 8 to April 18 | March | tulip poplar, dying elm, sycamore |
| South Dakota | April 18 to May 28 | May | just dead cottonwood, burned ponderosa, dying elm |
| Tennessee | March 15 to April 28 | April | dying elm, living white ash, tulip poplar |
| Texas | March 1 to April 15 | March | dying elm, just dead cottonwood, sycamore |
| Utah | April 15 to June 28 | May | burned conifer, aspen, cottonwood along water |
| Vermont | April 22 to May 30 | May | old apple, dying elm, living white ash |
| Virginia | March 25 to May 8 | April | tulip poplar, dying elm, living white ash |
| Washington | April 1 to July 5 | May | burned conifer, cottonwood, mixed conifer duff |
| West Virginia | April 1 to May 12 | April | dying elm, living white ash, tulip poplar |
| Wisconsin | April 20 to June 1 | May | dying elm, just dead cottonwood, living white ash |
| Wyoming | April 25 to July 5 | May | burned conifer, cottonwood, aspen |
A true morel is hollow from cap to base
One cut lengthwise settles it, and the agencies state it without hedging. A true morel is pitted like a honeycomb and opens into a single hollow chamber the whole way down. A false morel is reddish, wrinkled or brainlike rather than pitted, and its stalk is dense or chambered rather than open. Here are those sentences in full, from the Missouri Department of Conservation and the Forest Service.
“All Missouri true morels are completely hollow inside.”
Big Red False Morel, Gyromitra caroliniana The cut test, stated without qualification by a state agency. One cut lengthwise, one single open chamber from cap to base.
“The yellow morel has a honeycombed cap with yellow to yellow-gray to yellow-brown ridges and pits; it is completely hollow.”
Yellow Morel (Common Morel), Morchella esculentoides The positive identification: pitted like a honeycomb, ridges and pits, hollow through.
“Lookalikes: The poisonous or potentially toxic false morels (Gyromitra caroliniana and G. brunnea) are reddish and have wrinkled, lobed, or brain-shaped caps and dense (not hollow) stalks.”
Yellow Morel (Common Morel), Morchella esculentoides The contrast in one sentence from the same agency: wrinkled, lobed or brain shaped against pitted, and dense against hollow.
“The big red false morel is reddish brown, with a convoluted, brainlike cap and a whitish stalk that is chambered inside.”
Big Red False Morel, Gyromitra caroliniana Both halves of the false morel at once: the brainlike cap outside, the chambered stalk inside.
“You cannot tell how much gyromitrin a false morel contains just by looking at it.”
Big Red False Morel, Gyromitra caroliniana The reason the "my family has always eaten them" argument does not carry. The dose is invisible.
“For these reasons, we cannot recommend eating any false morel mushrooms.”
Big Red False Morel, Gyromitra caroliniana A state agency recommendation, in its own words, which is the strongest form this claim takes anywhere.
“If the head is attached to the stem halfway down, it is an edible half-free morel; if the head is attached only at the top of the stem, it is a potentially poisonous Verpa.”
Ecology and Management of Morels Harvested From the Forests of Western North America The second cut test, the one for Verpa rather than Gyromitra. Cut lengthwise and look at where the cap meets the stem: halfway down is a half-free morel, only at the very top is a Verpa.
“Some species in the genera Gyromitra and Verpa contain poisonous compounds and should be avoided.”
Ecology and Management of Morels Harvested From the Forests of Western North America Both lookalike genera in one federal line.
“It breaks down during digestion into a variety of toxic hydrazines including monomethylhydrazine (MMH), a component of rocket fuel. Because it has a boiling point of 189.5 ºF, cooking usually volatilizes the toxin.”
Ecology and Management of Morels Harvested From the Forests of Western North America What the toxin is and what cooking does to it. Usually volatilizes is the careful word, and the next finding is why that is not reassurance.
“Although this might explain why some individuals eat these species with seeming impunity, it also means that the cook or others in a poorly ventilated room can be exposed to the inhaled vapors. The toxin also can persist in cooking water and be absorbed through broken skin.”
Ecology and Management of Morels Harvested From the Forests of Western North America The part no blog carries. The person poisoned can be the one at the stove rather than the one at the table, and the cooking water carries it too.
“The toxins can accumulate in the body over time, and, as they accumulate with further consumption, there is a narrow threshold between no symptoms and a harmful or fatal reaction.”
Ecology and Management of Morels Harvested From the Forests of Western North America Years without symptoms is not evidence of safety, because the mechanism is cumulative and the margin at the end is narrow.
“Consumers of these fungi are gambling with their health and lives.”
Ecology and Management of Morels Harvested From the Forests of Western North America The Forest Service’s own summary sentence on eating Gyromitra.
“A number of problems were the result of people consuming morels raw – but everyone recovered within 24 hours.”
2011 NAMA Toxicology Committee Report: North American Mushroom Poisonings The one thing that goes wrong with correctly identified true morels: they are eaten raw. The dash inside the quote is the report’s own.
“There were no reported deaths.”
A 19-year longitudinal assessment of gyromitrin-containing (Gyromitra spp.) mushroom poisonings in Michigan Nineteen years of Michigan poison centre records, 118 gyromitrin cases, 91.5 percent of them Gyromitra esculenta, and no deaths. The cut test and the agency recommendation are what keep that record clean. The 14 percent fatality figure quoted around the web comes from a European case series published in 1967.
Identification is yours to make in your hand, and these quotes are the published sources rather than a substitute for them. Cook true morels before eating them.
Who to ask about picking on federal ground
Mushrooms are named as a special forest product in the federal programme, and the prohibition that free use and personal use permits are written against is paragraph (h) of 36 CFR 261.6. Which means the answer for a given national forest comes from that forest’s district office, and it differs from forest to forest and year to year.
“Examples include such products as floral greenery, Christmas trees and boughs, mushrooms, transplants (trees, shrubs or herbaceous plants), cones, medicinal plants, cuttings, herbs, nuts, berries, decorative wood, and pitch.”
Special Forest Products Mushrooms are a special forest product by name in the federal programme, which is why the permit question on a national forest belongs to the district office and the answer differs forest by forest.
“Removing any timber, tree or other forest product, except as authorized by a special-use authorization, timber sale contract, or Federal law or regulation.”
36 CFR 261.6, Timber and other forest products The prohibition every national forest free use and personal use permit is written against. Paragraph (h) of section 261.6, which is the governing section.
Morel forecasts by state
Each state page opens with the soil reading for a reference town, then the usual window, the host trees worth walking there, and the ground that comes on first. Enter a ZIP on any of them for your own woods.
Morel mushroom questions
More for spring foraging
The rating is a forecast of whether the soil has reached the published threshold, which tells you when to go; the walking finds the mushrooms. Soil temperature and soil moisture come from the Open-Meteo model for your coordinate, and the threshold, the floor and every other number in the forecast are quoted above with the source they came from.